The Abortion Act 1967 was frankly a disaster. The most emotionally effective argument in its favour was the prevention of illegal abortions (the number of which was grossly overstated at the time). The exceptions allowed by the Act – the physical or mental health of the mother or the severe disability of the child – turned out to be conditions of straw, as was well known to the lobbyists and, indeed, to anyone of common sense.

So nowadays abortion is effectively a matter of choice, and we have approaching 200,000 legal abortions a year. What is more, our culture has moved on from regarding abortion as a sad necessity; it has become a virtue. It is now politically incorrect to object to it. Various estimates have been made about the attitudes of Catholics, but it is safe to say that a substantial number walk by on the other side, and include many who effectively approve.

In following discussions on the internet I find that three arguments predominate. The first is the “hard cases” approach.

How could we deny abortion to the mother of a baby who is severely handicapped or a baby who is the result of rape? We are, of course, instinctively sympathetic. But it is useful here to establish whether the arguer has only such extreme situations in mind or whether he or she would also support abortion in normal circumstances. If so, we can leave aside the hard cases and focus on the principles.

This may lead quickly to considering the status of the entity in the womb. I use a neutral term here because our instinctive use of the word “baby” is likely to be attacked. So I settle for “individual human life” and then ask what part of this description does not apply.

The question of exactly when a human conceptus becomes an individual is tricky. The encyclical Evangelium Vitae does not settle this but teaches that the human being is to be respected and treated as a person from the moment of conception. Others, including respectable theologians, have argued that individuality is only achieved at the stage when the embryo can no longer split into identical twins. Since splitting may occur during the 10 days or so following conception, this has a bearing on the morality of very early abortion. (This issue, and indeed many others, is argued at length in Norman M Ford’s When Did I Begin?, published Cambridge University Press.)

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